1. Field of the Invention
The present invention relates to a substrate treatment apparatus having two substrate transport robots which transfer a substrate therebetween. Exemplary substrates to be treated include semiconductor wafers, substrates for liquid crystal display devices, substrates for plasma display devices, substrates for FED (Field Emission Display) devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photo masks, ceramic substrates, and substrates for solar cells.
2. Description of Related Art
One exemplary substrate treatment apparatus to be used in a process for producing semiconductor devices and liquid crystal display devices is of a single substrate treatment type adapted to treat a single substrate at a time. The substrate treatment apparatus of the single substrate treatment type includes an indexer robot which transports a substrate between a substrate container such as a cassette and a substrate transfer position, a plurality of treatment units, and a main transport robot which transports the substrate between the substrate transfer position and any one of the treatment units. The indexer robot and the main transport robot each have a hand capable of holding a single substrate. The treatment units are each adapted, for example, to perform a substrate surface treatment by supplying a treatment liquid (a chemical liquid or deionized water) to the substrate.
If foreign matter is adhered to the substrate, the foreign matter is liable to be transferred to the hand to contaminate the hand. Further, if the treatment liquid remains on the substrate after the substrate is treated with the treatment liquid, the treatment liquid is liable to be partly transferred to the hand which holds the substrate. If the transferred foreign matter and/or the transferred treatment liquid are accumulated on the hand, the accuracy of a substrate holding position at which the substrate is held on the hand is likely to be deteriorated. If the substrate is held at an inaccurate position on the hand, the substrate positioning accuracy at the substrate transfer position is liable to be deteriorated. This may result in failures (transportation failures) in substrate transfer between the indexer robot and the main transport robot, between the main transport robot and the treatment units and between the indexer robot and the substrate container, and the like. That is, the substrate is liable to fall out or to be broken.
To cope with such problems, it is conceivable to provide a hand cleaning unit as disclosed in JP-A-2000-68244. In an apparatus disclosed in JP-A-2000-68244, however, an object loading unit, the hand cleaning unit, an object cleaning unit, an object cleaning/drying unit and an object unloading unit are disposed around a transport robot in a so-called cluster configuration. In the cluster configuration, the hand cleaning unit takes up substantially as much space as that of the object cleaning unit or the object cleaning/drying unit (which are adapted to clean a semiconductor wafer). This disadvantageously reduces the space utilization efficiency, thereby correspondingly increasing the footprint (occupation area) of the apparatus.